A professor from Edinburgh University has issued a plea for red-headed volunteers to help his research into why so many Scots have ginger hair.

As many as 10% of Scots and Irish people have ginger or strawberry blond hair, while it is thought that up to 35% carry a recessive "ginger gene".

The figure is a far higher proportion than any other nationality and academics want to know why.

Before improvements in peoples' diets, many people developed rickets because they were not getting enough vitamin D, either in their food or through exposure to the sun.

It is thought that, since pale-skinned redheads needed less sunshine to get the necessary vitamins to fend off the condition, they flourished in cooler, less sunny climates.

The research is being conducted by dermatology professor Jonathan Rees as part of a £300,000 study into skin sensitivity, sun exposure and skin cancer.

Many Scots have red hair and pale skin

He said there may be two main reasons for Scotland's high proportion of ginger heads: "One is that there is selection for red hair, that is people who have pale skin have been selected in northern Europe.

"The other one is, if you like, that it is just chance and that it really doesn't matter.

"The reason for selection may be that people with pale skin are better able to make vitamin D in their own body.

"Vitamin D is made in the skin and, in the past, there were widespread deficiencies of vitamin D."

"People who carry the gene do not necessarily have red hair. But we do know they are sensitive to the sun.

"We want to find out to what degree people are sensitive and put it on an actual numerical scale."

Last month, the Health Education Board for Scotland warned that "macho" Scots were at risk from skin cancer for not taking care in the sun.

According to official figures:

125 Scots are diagnosed with skin cancer every week

199 people died of skin cancer in Scotland in 1998, compared with 1997 when 182 people died

In 1997 there were 6,739 cases of skin cancer in Scotland, up from 6,632 in 1996.

Anyone interested in taking part in the research can contact Professor Rees by email or by telephone on (0131) 536 2041.